Regular expression used in server_name directive (8 replies)

I am using a regular expression with a capture group in my server_name directive. It looks like:

server_name (?<account>.+)\.mydomain\.com$

The problem is that I want to expand it slightly and say anything except web3.mydomain.com. I.E.

something.mydomain.com matches, but web3.mydomain.com does not match.

How is this possible?